Soap manufacturing apparatus



Jan. 7, 1964 A. FINSBERG SOAP MANUFACTURING APPARATUS Original Filed Oct. 14, 1957 2 Sheets-Sheet 1 m m5 T 7., 5 in: EN sill V Jr mm F F. MY RB A 3 1 |||||l| :l'll I! I I I u" Fillllllll I ll .lllll HIS ATTORNEYS Jan. 7, 1964 A. FINSBERG 3,116,912

SOAP MANUFACTURING APPARATUS Original Filed Oct. 14, 1957 2 Sheets-Sheet-Z FIG. 2v

INVENTOR ARNE FINSBERG a M 86) g lvfiwc H IS ATTORNEYS United States Patent ()fiice 3,115,912 Patented Jan. 7, 19%4 3,116,912 SOAP MANUFACTURHNG APPTUS Arne Finsherg, Oslo, Norway, assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine Original application Get. 14, 1957, er. No. 690,127. Divided and this application Sept. 8, 1960, Ser. No. 54 736 Claims priority, application Great Britain st. 19, 1956 8 Claims. (Cl. 2594) This applicaton is a division of my co-pending application, Serial No. 690,127, filed October 14, 1957 which has matured into Patent No. 3,047,600.

The present invention relates to the manufacture of soap and in particular to the extraction of glycerine from soap produced by the saponification of fats and fatty oils, hereinafter for convenience referred to as fats.

In the orthodox manufacture of soap, as, for example, explained in the introduction to British Patent 612,014, the fats are generally boiled, by means of open steam, with caustic soda solution in large open pans.

It is customary next to separate the soap as far as possible from the resultinug homogeneous mixture of soap and aqueous liquor containing the glycerine, by adding a quantity of electrolyte (hereinafter referred to as salt), such as sodium chloride or concentrated brine, whereupon the homogeneous mass settles in two layers, the upper consisting of the soap and the lower layer, called lye, being an aqueous solution of the salt, glycerine and impurities from the fats. The soap so separated, a curd, usually contains of the order of 63% of fatty matter. By lye is means a solution of salt, the concentration of which is at least so great that soap will not dissolve in it (the critical concentration). After satisfactory separation, the lye is run off, purified and evaporated for the recovery of glycerine and salt. The curd soap which remains in the pan is boiled with a suitable amount of water to close the curd. The contents of the pan are then again opened by addition of salt. If this process is repeated a number of times, most of the glycerine can be washed, that is, extracted from the soap.

The soap is next fitted to separate it into an upper layer of neat soap and a lower layer of nigre. This fitting operation is described in the introduction to British Patent 623,224.

The orthodox soap-making process outlined above may advantageously be substituted by continuous processes, or a series of processes where one or two of the three steps referred to are continuous. Especially the continuous washing of soap offers considerable advantages; continuous extraction of glycerine from soap may be more complete or cost less than batchwise extraction. It has previously been proposed to wash soap continuously by mixing intimately a continuous stream of soap with a continuous stream of brine at or above the critical concentration, thus facilitating the removal of glycerine from the soap to the lye, and then allowing the lye to separate from the soap. This separation may take place according to the method described in British Patent 612,014. The degree of washing of the soap is generally determined by economic considerations; a great quantity of lye allows almost complete extraction of glycerine (but it becomes expensive to evaporate the lye); a smaller quantity, economical to evaporate, will allow less complete extraction.

It is an object of the present invention to provide an improved process for continuously washing soap. The process for washing soap according to the invention is one in which unwashed soap and fresh lye are continuously supplied to a vessel, the soap to be washed is intimately mixed with fresh lye, the lye is separated from the soap, and separated soap and lye are continuously removed from the vessel, a portion of the lye continuously removed being returned and directly mixed with the soap which is washed with the fresh lye, this portion of separated lye being at least equal in weight to the quantity of fresh lye introduced.

Fresh lye may be lye free from glycerine or lye already containing some glycerine; for instance it may already have been used to wash soap of lower glycerine content.

Preferably the fresh lye to be intimately mixed with the soap is in the form of a continuous stream, and preferably also the soap to be intimately mixed with the fresh lye is in the form of a continuous stream. The soap to be washed and the portion of returned separated lye are advantageously mixed separately of the bulk of soap and lye contained in the vessel in which separation takes place. The mixing can be altogether outside the vessel or it can be in a compartment within the vessel. The fresh lye can also be mixed with the soap to be washed, separately from the bulk of soap and lye contained in the vessel in which separation takes place. Conveniently the washing by separate mixing is substantially complete before the mixture enters that part of the vessel where separation talces place. Separate mixing can take place in a tube through which the mixture flows to that part of the vessel where separation takes place.

Particularly satisfactory results can be obtained when the portion of separated lye removed from the vessel, returned and directly mixed with the soap is at least three times the weight of the fresh lye introduced. T he portion may be as much as live or ten times the weight of fresh lye introduced if this is desired.

The process is conveniently carried out in a series of vessels, in each of which a washing operation takes place. Thus the soap and lye can be passed through at least two vessels in series, in each of which the process of the invention is carried out, and the soap and the lye passing through the series of vessels can be counter-current, that is to say, the general movement of lye transported through the series of vessels is in the opposite direction to that of the soap. The series of vessels can take the form of a number of compartments into which a large soap pan is divided by partitions.

Sutiable apparatus for carrying out the process of the invention comprises at least two vessels in series, each of which is provided with a mixing device discharging into it, the mixing device of any vessel subsequent to the first vessel of the series being arranged within the preceding vessel. Preferably the mixing device of every vessel subsequent to the first one is arranged within the preceding vessel. The mixing device of the first vessel is preferably arranged within the last vessel.

In a particularly suitable form of apparatus, the inlet of a mixing device is centrally disposed in the preceding vessel and is, except for the mixing device of the first vessel, ararnged so that liquid contained in the vessel within which the mixing device is disposed can overflow into that mixing device. Means can be provided for introducing liquid from any vessel into the mixing device arranged in any preceding vessel. Means can also be provided for promoting the how of liquid through the mixing device, and an ejector can be used; with an ejector, a stream of one liquid is forced through a constricted orifice within a tube carrying another liquid, which is thus drawn along the tube.

The invention will now :be described with reference to the accompanying drawings, in which FIGURES 1 to 3 each show a diagrammatic flow sheet of a particular way of carrying out the invention.

FIGURE 1 shows an arrangement in which four washing units are combined. To facilitate the understanding of this arrangement it is pointed out that funnel 28 (and similar funnels) receiving soap and recycled lye as well as fresh lye has been moved to the middle of the adjacent compartment. Funnel 28 accordingly belongs to section B although it is disposed within section A. In this way soap overflows in the middle of the compartment, instead of at the edge thus reducing the average distance soap has to flow from compartment to compartment.

Fresh lye containing substantially no glycerine enters the arrangement through conduit 27 into funnel 4d dis posed Within section D. Crude curd soap enters the funnel 28 of section B through conduit 29, together with lye circulating from section B through conduit 39. Of all the lye in the various sections, lye separating in section B is richest in glycerine, and some is therefore also removed at 30 in a quantity equal to the quantity of transported lye introduced into the funnel 28 of section B at 31. This transported lye which replaces lye removed at 30 is fresh lye so far as section B is concerned, but already contains glycerine (though less than in the removed lye) and leaves the bottom of section C via a conduit and pump 39 through the valve 32, which is governed by the interface float 33, and thence through conduit 34 into the tunnel 23 of section B. The quantity of lye removed from section B and not recycled is controlled by the valve 35, governed by the interface float 36. The curd soap entering funnel 28 of section B is mixed by the device 37 with the fresh lye and lye recycled from the bottom of section B by a pump 39 to the mixing device 37, and the resulting emulsion is discharged through the tube 3% into section B. In section B the soap separates from the lye by rising, and when it has reached the surface it overflows into funnel 40 of section C (disposed within section B) where it is mixed with recycled lye from section C delivered by the pump 39 as well as with fresh lye transported from section D. This operation is repeated in the remaining two sections. Section A is shown twice for an easier understanding of the process.

FIGURE 2 helps to demonstrate how the soap receives its last wash in the funnel 41 of section A (disposed within section D) by means of fresh lye 27 introduced there to gether with recycled lye from section A. The soap/lye emulsion leaving funnel 41 discharges into section A and separates into an upper layer of soap and a lower layer of lye as described above. The soap overflows into gutter 42 from which the soap is removed, having received its final wash.

The position of the soap/lye interface is of no conse quence for the operation of the process, and the soap/ lye emulsion may be discharged into either the lye layer or the soap layer, or into the interface itself; the choice will largely depend on economic considerations. It may be advantageous to have a deep soap layer (whereupon soap takes longer to rise and a more complete separation of lye and soap is effected) or it may be advantageous to have a relatively shallow soap layer (to reduce the quantity of soap to be washed).

FIGURE 3 shows an arrangement of six washing units.

Four or six washing units, or even greater numbers, may be cheaply and yet very compactly arranged. Thus, for example, existing soap pans may be divided into these units by simply erecting dividing Walls (which may be of light and cheap material, as the walls do not have to resist high pressures).

A further advantage of the invention is that the successful operation of the process is not dependent on the condition of the soap to be washed; it may be closed or open, provided it is reasonable liquid. If the soap contains large amounts of Water, which would, of course, reduce the concentration of the lye below its critical concentration, then it can be rectified simply by feeding into the soap a continuous stream of concentrated brine.

A nigre can be used for washing soap according to the process of the invention. However, the addition of nigre to the first of a multi-stage washing operation as, for example, section A illustrated in FIGURE 1 is not recommended as the comparatively low content of glycerine in nigre would adversely affect the efiiciency of the system.

d Nigre may advantageously be added in later stages, for example, section C where the glycerine has already been removed to about the level generally found in nigre. The excess of water in nigre over the content in an ordinary curd soap can easily be rectified as described above by adding a continuous stream of concentrated brine.

The following example illustrates a process of the invention using relatively simple equipment, and the data provided can readily be adapted for a process using more elaborate equipment such as is illustrated in FIGURES l, 2 and 3.

Example A soap pan of 3.9 x 3.9 metres cross section and 4 metres high was divided into four compartments of equal size by two dividing walls crossing each other in the centre. Each compartment was provided with a vertical wall which, when the compartment contained soap and lye, rose above the level of the soap and dipped into the soap layer to within 0.5 metre of the soap/ lye interface, thus dividing each compartment into a rnixing zone and a separating zone. The level of the dividing walls was such that soap could overflow by gravity from the separating zone of the first compartment to the mixing zone of the second, then to the third and fourth in turn, and finally into a gutter taking away the washed soap. Apertures in the walls of the compartments were provided enabling lye to enter the fourth compartment and pass in turn through the third, second and first compartments and out of the system. A

A continuous stream of crude curd soap at 95 C. in the closed condition containing about 58% fatty acids was fed into the first compartment of the apparatus at the rate of 5 tons per hour. Counter-current to this, 3 tons of brine, containing 11.5% by weight of sodium chloride and at a temperature of C., was continuously introduced into the fourth compartment. In each compartment brine was recirculated through the soap in the mixing zone by means of a centrifugal pump at a rate of 18 tons per hour. The portion of separated lye removed from the compartments in each instance, returned and directly mixed with the soap (that is, recycled lye) was accordingly five times the weight of the fresh lye introduced. The glycerine content of the crude crud was 4% by weight and was reduced to 0.6% after the soap had been finally washed; on leaving the system the soap still had a fatty acid content of about 58%. The content of glycerine in the brine entering the first compartment was 0.2%, while 6.8% of glycerine was found in the final lye; in the inter-mediate compartments the content of glycerine was between these figures. An aqueous solution of caustic soda was continuously added to the brine in a quantity suflicient to keep the lye well on the alkaline side. In the gutter aqueous solutions of salt were added in suitable amounts to fit the soap, which was then allowed to settle in a pan.

I claim:

1. Apparatus for washing soap, comprising at least two vessels in series, each of which is provided with a mixing device discharging into it, each vessel at its lower portion being connected to a pipe discharging into the mixing device of said vessel, means for promoting a flow of liquid in each of said pipes, and a bypass line branched off from each of said pipes downstream of the means for promoting a flow of liquid, the bypass line of each vessel subsequent to the first vessel discharging into the mixing device of the preceding vessel.

2. Apparatus according to claim 1, in which the mixing device of every vessel subsequent to the first one is arranged within the preceding vessel.

3. Apparatus according to claim 2, in which the mixing device of the first vessel is arranged within the last vessel.

4. Apparatus according to claim 1, in which the inlet of a mixing device is centrally disposed in the preceding vessel and is, except for the mixing device of the first vessel, arranged so that liquid contained in the vessel Within which the mixing device is disposed can overflow into that mixing device.

5. Apparatus according to claim 2, in which the inlet of a mixing device is centrally disposed in the preceding vessel and is, except for the mixing device of the first vesse-l, arranged so that liquid contained in the vessel within which the mixing device is disposed can overflow into that mixing device.

6. Apparatus according to claim 3, in which the inlet of a mixing device is centrally disposed in the preceding vessel and is, except for the mixing device of the first vessel, arranged so that liquid contained in the vessel within which the mixing device is disposed can overflow into that mixing device.

7. Apparatus according to claim 1, in Which means are provided for promoting the flow of liquid through the mixing device.

8. Apparatus according to claim 1, in which an ejector is provided for promoting the flow of liquid through the mixing device.

References titted in the file of this patent UNlTED STATES PATIENTS 2,091,709 Hampton Aug. 31, 1937 2,523,523 Robinson et a Sept. 26, 1950 2,562,207 Owen July 31, 1951 2,630,376 Dunn Mar. 3, 1953 2,723,838 Peters Nov. 15, 1955 2,879,144 Thornton Mar. 24, 1959 2,884,231 Pyle et a1 1. Apr. 28, 1959 

1. APPARATUS FOR WASHING SOAP, COMPRISING AT LEAST TWO VESSEL IN SERIES, EACH OF WHICH IS PROVIDED WITH A MIXING DEVICE DISCHARGING INTO IT, EACH VESSEL AT ITS LOWER PORTION BEING CONNECTED TO A PIPE DISCHARGING INTO THE MIXING DEVICE OF SAID VESSEL, MEANS FOR PROMOTING A FLOW OF LIQUID IN EACH OF SAID PIPES, AND A BY-PASS LINE BRANCHED OFF FROM EACH OF SAID PIPES DOWNSTREAM OF THE EMANS FOR PROMOTING A FLOW OF LIQUID, THE BY-PASS LINE OF EACH VESSEL SUB- 